using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Tetris
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;

        private Texture2D _Background;
        private Texture2D _IntroScreen;
        private Texture2D _PauseScreen;

        private Playfield _Playfield = new Playfield();

        private GameState currentState = GameState.IntroScreen;

        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";

            graphics.PreferredBackBufferHeight = 768;
            graphics.PreferredBackBufferWidth = 1024;
        }

        private enum GameState
        {
            IntroScreen,
            Playing,
            Paused,
            GameOver
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);

            InitializeGraphics();
        }

        private void InitializeGraphics()
        {
            _Background = Content.Load<Texture2D>("Images/Background");
            _IntroScreen = Content.Load<Texture2D>("Images/IntroScreen");
            _PauseScreen = Content.Load<Texture2D>("Images/PauseScreen");
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            // TODO: Add your update logic here
            float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds;
            
            KeyboardState akeyboard = Keyboard.GetState();

            if (akeyboard.IsKeyDown(Keys.Escape) == true)
                currentState = GameState.Paused;

            UpdateGameObjects(elapsed, akeyboard);

           
            base.Update(gameTime);
        }

        private void UpdateGameObjects(float elapsed, KeyboardState akeyboard)
        {
            if(akeyboard.IsKeyDown(Keys.Space) == true)
            {
                if (currentState == GameState.IntroScreen)
                    currentState = GameState.Playing;
            }
            if (akeyboard.IsKeyDown(Keys.Escape) == true)
            {
                if (currentState == GameState.Playing)
                    currentState = GameState.Paused;
            }
            if (currentState == GameState.Paused)
                if (akeyboard.IsKeyDown(Keys.Space))
                    currentState = GameState.Playing;
            
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            graphics.GraphicsDevice.Clear(Color.White);

            spriteBatch.Begin();

            if (currentState == GameState.IntroScreen)
            {
                spriteBatch.Draw(_IntroScreen, new Rectangle(0, 0, 1024, 768), Color.White);
            }
            else if(currentState == GameState.Playing)
            {
                spriteBatch.Draw(_Background, new Rectangle(0, 0, 1024, 768), Color.White);
            }
            else if (currentState == GameState.Paused)
            {
                spriteBatch.Draw(_PauseScreen, new Rectangle(0, 0, 1024, 768), Color.Blue * 0.5f);
            }

            spriteBatch.End();
            base.Draw(gameTime);
        }
    }
}
